This paper provides an overview of the work of Herbert Simon and his ideas about rational decision making. By his own standards, Simon is an economist who works in the tradition of Adam Smith and Alfred Marshall. The central theme in Simon’s research is how human beings organize themselves in different structures of distributed decision making in order to achieve a degree of rationality that is higher than which can be attained by the individual. In this realm his main preoccupation are hierarchic organizations such as the business firm and the computer. Simon sharply contrasts his views with the EUT, the dominant view on rational decision making in economics and other social sciences.